1. Field of the Disclosure
This disclosure relates generally to drill bits that include sensors for providing measurements relating to detection of gamma rays from formations.
2. Brief Description of the Related Art
Oil wells (wellbores) are usually drilled with a drill string that includes a tubular member having a drilling assembly (also referred to as the bottomhole assembly or “BHA”) with a drill bit attached to the bottom end thereof. The drill bit is rotated to disintegrate the earth formations to drill the wellbore. The BHA includes devices and sensors for providing information about a variety of parameters relating to the drilling operations, behavior of the BHA and formation surrounding the wellbore being drilled (formation parameters). A variety of sensors, including gamma ray detectors, generally referred to as logging-while-drilling (LWD) sensors or measurements-while-drilling (MWD) sensors, are disposed in the BHA for estimating properties of the formation. Such sensors, however, are placed several feet from the drill bit and generally cannot provide formation information proximate the drill bit as the drill bit is cutting the formation. But certain type of sensors placed in the drill bit can provide useful information about the formation proximate the drill bit at substantially the same time as the drill bit is cutting the formation. It is desirable to place certain sensors, such as gamma ray sensors, at the face of the drill bits. Sensors placed at the face of the drill can reduce mechanical strength of the drill and thus it is desirable to locate such sensors at bit face locations that are less prone to reducing the mechanical integrity of the drill bit.
The disclosure herein provides a method of selecting locations for sensors on the drill bit and drill bits that include sensors at such selected locations.